Death penalty should be abolished

The mentally retarded Imran Ali was hanged today. He was alleged to have raped and killed eight year old Zainab (the cops said he had killed many other little girls as well, but you can't believe what our cops say). The parents of the dead girl had demanded that the killer be hanged in full view of the public, but fortunately the court did not agree. 
People have often asked me why I say that killers and rapists should not be executed. The main reason, of course, is that in third world countries like Pakistan, innocent men and women are likely to be hanged. In the UK, a Muslim man was hanged in 1957 for a murder which he did not commit. The actual killer confessed on his death bed to the crime, the government realized its mistake and repealed the death penalty. I'm firmly convinced that many innocent people have been killed by the state for no fault of their own. Sometimes people are implicated in blasphemy cases by rivals who want their lands, or due to old enmity. It is very easy to give ten thousand rupees to a police inspector and file a case of murder against anyone you want. A Christian woman has been charged with blasphemy after a quarrel which resulted after she drank water from a well from which only Muslims were supposed to drink. Some Christians have been burnt alive after someone accused them of uttering blasphemous words or sentences. To give him credit, the notoriously corrupt AAZ didn't allow anyone to be executed in his five year stint as president of the country.
I believe that capital punishment should be abolished entirely, whatever the crime committed. It doesn't serve the purpose of preventing others committing rape or murder and other crimes. In Saudi Arabia, heads are chopped off for smuggling drugs and hands are cut for theft, yet both crimes continue to occur. That is why the death penalty is never imposed in highly civilized countries like the UK and the European Union. We should follow suit.